In the case of a flying object such as a glider or the like which does not use power during flight, it is important to find ascending air current (thermal). In order to find the thermal, it is required to pay attention to changes in wind or temperatures, movement of birds or insects, shapes of clouds, or the like. However, it is difficult to find the thermal from such information without experience.
Japanese Utility Model Application Publication No. S63-189800 discloses a technique for detecting an ascending air current by comparing temperatures detected by thermosensitive devices provided at a right and a left wing.
Japanese Patent Application Publication No. 2005-82018 discloses a technique for estimating an ascending air current by measuring an air current or the like.
For example, in the case of a wireless control device and a model glider, an operator determines a thermal from movement of a fuselage of the model glider in the sky. However, this requires experience and no deflection of the fuselage. It is difficult even for a skilled person to assemble the fuselage without deflection, adjust any deflection or set a transmitter.
Further, when the fuselage is flying at a high altitude, it is difficult to detect the movement of the fuselage with naked eyes. Therefore, it is very difficult to determine the thermal from the movement of the fuselage.
Accordingly, it is required to detect an air current with high accuracy by a small and simple configuration that can be installed at a wirelessly controlled flying object.